Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 260601

National Weather Service Jackson KY
201 AM EDT Fri May 26 2017

Issued at 201 AM EDT FRI MAY 26 2017

Inserted some fog into the forecast for tonight given lingering
low level moisture and the brunt of the cloud cover exiting off to
the east. Subtle dry air advection may keep any dense fog at bay,
mainly being confined to the valleys. Would expect perhaps a
little more development later tonight as clouds further clear
underneath an approaching surface ridge axis.


.SHORT TERM...(This evening through Friday night)
Issued at 408 PM EDT THU MAY 25 2017

An upper level low pressure system continues to shift NE of Kentucky
this afternoon, pulling with it the surface low which is currently
located over north-central Ohio. Moisture from this system has
impacted much of eastern KY today with widespread stratiform rain.
However, as the system continues to shift NE of the region, this
rain will continue to move east and taper off throughout the
afternoon/evening. With no instability to work with, continued with
no thunder in the forecast during this time.

Upper level ridging and surface high pressure will work in overnight
tonight, but llvl moisture may linger a bit in the form of low
clouds, eventually breaking up by daybreak Friday in many locations.
A warm front moving in to our north will likely keep cloud cover
in place across the NE CWA. According to the latest soundings,
this llvl cloud cover should be enough to prevent fog in most
locations, though can`t rule out some isolated valley occurrences.

During the day Friday, another surface low pressure system will be
located over the Southern Plains tracking NE into the Mid
Mississippi Valley. This will send a warm front eastward into
Kentucky during the day Friday into Friday night, with the return of
southerly winds pulling moisture off of the Gulf of Mexico.
Temperatures will shoot up to near 80 by Friday afternoon, compared
to our 60 degrees today. Precipitation will also start moving in
along the Ohio River Friday night, before spreading into our region
during the day Friday. This could bring some pops into our northern
CWA to round out the short term portion of the forecast. However,
after looking at the latest NAM12 forecast soundings, all moisture
should be confined to a fairly shallow layer in the llvls, with a
very strong inversion located just above followed by dry air aloft.
In such a setting, there is nothing to support convection, so kept
with only rain mention in the grids during the overnight. Southerly
flow will also help keep overnight temps from bottoming out Friday
night/Saturday morning, only falling to the low to mid 60s.

.LONG TERM...(Saturday through Thursday)
Issued at 447 PM EDT THU MAY 25 2017

The long wave pattern reveals amplifying flow once again into
next week. An upper level low will deepen across south central
Canada, with troughing taking shape across the Mississippi Valley
into early next week. A baroclinic zone will be laid out initially
along the Ohio Valley, with several short wave troughs traversing
the flow. This will bring continued storminess to eastern
Kentucky, with the possibility of severe weather as well as flash
flooding, given the already wet conditions in place. Will continue
to highlight these threats in the HWO.

Cyclonic flow will linger into next week across the Great Lakes
and Ohio Valley regions, as the Canadian upper level low
gradually spirals its way east. The baroclinic zone will drop
south, yielding some return of drier weather; however, a few POPs
may linger during peak heating in places between Tuesday and
Thursday, with the surface boundary still in the vicinity of the

For temperatures, slightly above normal readings will build back
into the region for this weekend as highs return to around the 80
degree mark. Humidity levels will also be on the rise. Once the
front exits to the south on Monday, generally near to slightly
below normal readings can be expected through the rest of the
period, with lower humidity levels.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)

VFR ceilings have materialized across eastern Kentucky, with
perhaps some lingering MVFR ceilings in far eastern Kentucky near
the Virginia border. An approaching ridge of high pressure will
continue to clear skies out overnight, thus promoting the
potential for fog development. This may end up being mostly
confined to valley locales, but believe all sites stand a chance
of at least MVFR visibilities by daybreak Friday given recent
rainfall. These should improve to VFR levels by mid morning with
VFR conditions prevailing through the remainder of the day and
evening. Will have to watch a potential round of showers and
thunderstorms this evening near the Ohio River, but have kept any
SH or CB mention silent at KSYM for now until trends in this
development become better defined. Southwesterly low level wind
shear may also warrant watching for this evening, but this
currently looks too weak, around 30 knots, to be concerned with
at this time.




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